Oddly enough, building ARBs for people isn’t part of my life’s plan. Well, unless you paid me enough anyway and that’d make it the world’s most expensive ARB.

Come on though, it’s easy to make. I know you ought to use spring steel but cooking stuff seems to work fine!

Tim

Your plan sounds good. The front end of my Mojo is slightly different to yours (outboard shocks & sierra uprights, unlike later Mojos/Riots/Spectres) but I think the geometry in terms of roll centres etc is likely to be pretty similar.

Do you take ARB commissions?

My approach is going to be pretty much as I did for the Fury: a bar running in aluminium blocks bolted to the chassis, two actuating arms welded to the ends of the bar (previously I’ve just bent a solid bar but this time I shall have separate arms on the ends of a solid, or perhaps tubular if I can get the right material, bar), and actuating rods made up of aluminium shafts with 5/16″ rod ends the ends. The rod ends will connect to one of a series of holes drilled in the arms and a tab welded to the bottom wishbone. The issue is always to get the actuating shaft long enough so that the bar doesn’t bind up at the extremes of travel. It’s usually pretty easy to do for the front ARB as there isn’t a drive shaft in the way.

T

Exactly. In fact the plan is to put the cr[ou]tch strap bush in that same plate. Admittedly the top of the side bit is 25mm above the top of the centre bit, but that’ll be all covered in foam anyway.

As to cutting the tub up, there’s something about that that I just don’t like. I may convince myself that I’m being daft though; I ordered the roll cage steel today so I’ll have to come to some conclusion soon. I think much of my problem is that I’m going to have to modify the tub anyway to stretch it backwards and I’m wary about ending up with a jigsaw of bits of GRP that don’t fit together even as well as one needs in a race car.

Your plan with the slots in the rear deck was the same conclusion I reached on how to do it on my (entirely imaginary) Spectre. I hadn’t appreciated the bolt-on stays were to allow you to remove the centre tub. I think I’d be tempted to cut away the section of the centre tub which goes around the cage (the bit which the seatbelt bolts pass through) and make a flange with a Bighead fastener in it for the centre tub to attach to in order to hold them together.

The plan is to cut slots in the rear deck so it’ll fit over the rear stays; it’ll probably have to slide in from the rear so that the slots are parallel with the car’s axis. In fact, I’ll probably make a virtue out of it and made an ally panel under the slot to support the front of the rear bodywork. The swinging legs will mean that the central tub can be taken off as a single piece as it ideally fits around the roll cage, like the Fury one does. The alternative is, of course, to just make the tub in two parts anyway and that is still an option which might actually be quite a good idea when I come to look at having to lengthen the bodywork anyway. Be nice to have the option though. I did wonder about using pins and a spring clip, but I’m not sure I’d trust it, and the relevant diagram in the BB has a proper bolt there. As you say, having to have a spannner to check the oil level would be a real PITA…

T

Does the swinging rear stays plan mean that you’ll have to undo 2 bolts every time you want to poke at the engine, or does when you say clevis does this mean you’ll be using clevis pins and a spring clip/R-clip? Having to wield spanners just to check the oil levels sounds like rather a faff…